Technically they are nearly identical — @Service, @Repository, and @Controller are all meta-annotated with @Component, so all four make a class a scannable bean — but they are not perfectly interchangeable, and @Repository in particular carries real extra behavior. The honest senior answer is "functionally almost the same, semantically distinct, with one concrete exception."
They share one mechanism
All four are stereotype annotations. @Service, @Repository, and @Controller are themselves annotated with @Component:
@Component // <-- this is why component scanning picks @Service up
public @interface Service { ... }So component scanning treats them the same way: detect the class, register a bean definition, instantiate as a singleton. You could annotate everything with plain @Component and the app would wire up identically.
So why have four?
1. Semantics / readability. They mark architectural layers — @Controller (web), @Service (business logic), @Repository (persistence). A reader instantly knows a class's role. This is the main reason and it's not nothing.
2. @Repository adds real behavior: exception translation. When a PersistenceExceptionTranslationPostProcessor is present (Boot configures it for you), beans marked @Repository get a proxy that translates vendor-specific persistence exceptions (Hibernate's JDBCException, raw SQLException) into Spring's consistent DataAccessException hierarchy. Plain @Component does not get this.
@Repository // gets persistence-exception translation
public class JpaOrderRepository { ... }3. AOP and pointcut targeting. Because stereotypes are distinct annotations, you can write aspects or pointcuts that target a layer — e.g. @within(org.springframework.stereotype.Service) — which you couldn't do if everything were @Component.
4. Tooling and future-proofing. Frameworks and IDEs key off the specific stereotype, and Spring reserves the right to attach more behavior to a specific one later — @Repository is precedent for exactly that.
@Controller / @RestController
@Controller is a stereotype the web layer (DispatcherServlet) scans for to find request handlers; @RestController is @Controller + @ResponseBody. The web framework specifically looks for @Controller, so swapping it for @Component would break MVC mapping.